re(ui): decode keyframe +12 as screen-plane rotation in degrees

The rotated quads on the title screen come from the keyframe block after
all. The earlier negative -- "every GP_TITLE build 4 element has all three
angle words at zero" -- read the right bytes over too small a region: it
walked the top-level declaration table, and the rotated elements are the
nested leaf records ptloop01.rat / ptloop02.rat.

Confirmed against the framebuffer rather than against our own renderer.
The two records declare +12 = 30 and -45; the GPU capture submits their
quads at +30.26 and -45.28 degrees -- magnitude and sign, two different
values. Corroborated by shape in GP_BUNK 117ca14f, where +12 ramps
0 -> 360 with position, scale and alpha constant: a spin in place.

Identifying which draw it was needed edge lengths, not bounding boxes:
400x1076 and 400x1444 against pteff03/pteff03a 399x180 at the elements'
two different declared scales, 600% (1080) and 800% (1440). The same test
names three known-positives in the capture (ptlogo1, ptcopyright,
ptbtn00), so it passes its own control.

Keyframe gains rotation_deg plus unknown_4/unknown_8, carried rather than
dropped. NOT rendered -- ui_layout::blit is axis-aligned only, so the
reference renderer and the port will both draw these upright until a
rotating blit exists.

The census tool ships with the trap that broke its first version: nested
RATC blobs are not 4-byte aligned, so an aligned scan found 0/3 of its
own control blocks and missed 16 341 blocks. Disc-wide +12 is non-zero in
14.50 % of 83 862 blocks.

sylpheed-formats tests, SYLPHEED_DISC set: 131 passed, 0 failed across the
6 suites finished at commit time; the run had not yet completed.

docs/re/REFUTED.md

@@ -40,11 +40,25 @@ neighbourhood, not just the line.
   −292…1012 in screen space; the swoosh is a band at y 126…360.
   [`ui-title-build-map.md`](ui-title-build-map.md)
 * "the keyframe words at `+4`/`+8`/`+12` are always zero" → they are non-zero in
-  4.81 %, 4.56 % and 15.82 % of 72 287 blocks disc-wide, reading as **degrees**
-  (±180, ±90, 120). The original note was a sample artefact.
-* "those angle fields are where the title's rotated quads come from" → **no** —
-  every `GP_TITLE` build 4 element has all three at zero.
-  [`ui-title-build-map.md`](ui-title-build-map.md)
+  **4.76 %, 4.62 % and 14.50 % of 83 862** blocks disc-wide, reading as
+  **degrees** (±180, ±90, 120, 360). The original note was a sample artefact.
+  (Superseded figures: an earlier count of 72 287 blocks missed every nested
+  record — see the alignment entry below.)
+* ~~"those angle fields are where the title's rotated quads come from" → **no** —
+  every `GP_TITLE` build 4 element has all three at zero.~~ → **that refutation
+  was itself wrong, and is withdrawn (2026-08-28).** `+12` *is* exactly where
+  they come from. Build 4's **top-level** elements do all read zero; the rotated
+  quads belong to its two **nested** leaf records, `ptloop01.rat` (`+12` = 30)
+  and `ptloop02.rat` (`+12` = −45), which the census never opened. Measured
+  off the GPU: **+30.26°** and **−45.28°**.
+  [`ui-keyframe-rotation.md`](structures/ui-keyframe-rotation.md)
+* "the rotated draw's element cannot be named from the capture" → refuted; its
+  quads' **edge lengths** name it. 400 × 1076 and 400 × 1444 match `pteff03`
+  399×180 at 600 % and `pteff03a` 399×180 at 800 % — two different heights, both
+  landing. [`ui-keyframe-rotation.md`](structures/ui-keyframe-rotation.md)
+* "a keyframe-block scanner may assume 4-byte alignment" → refuted; it found
+  **0/3** of its own control blocks and under-counted the corpus by 16 341
+  blocks. Nested `RATC` blobs start at odd offsets (`0xbb5966`).
 * "the game passes a pink per-vertex colour for the title swoosh" → **refuted by
   draw capture.** Every vertex colour in the capture is `<alpha>FFFFFF`, white RGB.
 * "the swoosh discrepancy is undecodable" → **solved**: the game submits it as two